X-ray imaging devices are used to obtain information about internal structures within an object of interest by irradiating the object with an X-ray beam generated by an X-ray source. For example, in medical X-ray imaging, those devices are used to obtain information about the inside structures (bones, organs . . . ) within a human body. An X-ray imaging device can acquire two-dimensional or three-dimensional images. For example, an X-ray imaging device can be a conventional X-ray imaging device for acquiring two-dimensional X-ray projection images, a C-arm X-ray imaging device, or a computer tomography (CT) device.
Conventionally, an X-ray source, often called X-ray tube, comprises a tube housing and an X-ray tube insert inside the tube housing. The X-ray tube insert is a vacuum tube, and comprises a so-called tube insert cap for sealing the tube. Inside the tube insert cap, there are a cathode for emitting electrons and an anode for emitting X-ray beam upon receiving the electrons. The tube housing protects the fragile vacuum tube. Typically, the tube housing is opaque to X-ray radiation and has an opening for allowing the X-ray beam to pass through. The emitted X-ray beam is directed towards a region of interest, for example a part of the patient's body. Since different tissues and/or bones within the patient's body have different levels of X-ray absorption, the X ray beam having passed through the region of interest is attenuated accordingly. The X ray beam having passed through the region of interest is then detected by an X-ray detector and the signal indicative of detected X-ray intensities, and the detected signal contains information about the internal structure within the patient's body and such information is retrieved, e.g. by forming X-ray images, accordingly.
A collimator can be used to collimate the X-ray beam generated by the X-ray source to be a slice of the X-ray beam passing through the region of interest. The collimator can be used to provide collimation for the X-ray beam so as to limit the size of the X-ray beam after passing through the collimator. For example, in typical CT systems, collimation is achieved by a blade set comprising of two moveable blades and a moveable plate with fixed slots or cams.
US2015/173692A1 discloses a device including a radiation source to emit radiation from a focal spot toward a volume of interest and a dynamic collimator located between the focal spot and the volume of interest.
WO2012/058207A2 discloses an X-ray beam scanner comprising a X-ray source and a collimator, which is stationary during image scanning, for collimating the X-ray beam so as to change the extent of the scan. The collimator is a standalone unit and is located outside the x-ray source, namely outside the tube housing which has an opening thereon. The inventor has recognized that such X-ray source and collimator as a whole are complex in structure.